Method of depositing a high-emissivity layer

Abstract

A method of depositing a high-emissivity layer on a substrate comprising RF sputter deposition of a carbide-containing target in an atmosphere of a hydrocarbon gas and a noble gas. As the carbide is deposited on the substrate the hydrocarbon gas decomposes to hydrogen and carbon. The carbon deposits on the target and substrate causing a carbide/carbon composition gradient to form on the substrate. At a sufficiently high partial pressure of hydrocarbon gas, a film of high-emissivity pure carbon will eventually form over the substrate.

The embodiments of this invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A method for depositing a carbon layer on a substrate comprising: providing a chamber for RF reactive sputter deposition,   providing within the chamber a substrate and a target comprised of a carbide compound,   providing a noble gas and a hydrocarbon gas to the chamber,   applying RF power to the target to sputter deposit the carbide compound onto the substrate and to decompose the hydrocarbon gas to hydrogen and carbon such that carbon deposits on the target and substrate whereby a layer having a carbide/carbon composition gradient develops on the substrate, and   maintaining the partial pressure of hydrocarbon gas sufficiently high so that the carbon accumulation rate on the target is greater than the sputter removal rate, whereby a continuous layer of carbon will form on the target and a layer of carbon will form over the carbide/carbon gradient on the substrate.   
     
     
       2. The method of claim 1 wherein the hydrocarbon gas is acetylene. 
     
     
       3. The method of claim 2 wherein the partial pressure of acetylene at least 0.034 Pa. 
     
     
       4. The method of claim 3 wherein the total pressure in the chamber is at least 3.33 Pa. 
     
     
       5. The method of claim 1 wherein the target is comprised of a carbide of at least one element selected from the group consisting of Si, B, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W. 
     
     
       6. The method of claim 5 wherein the target is comprised of tungsten carbide. 
     
     
       7. The method of claim 1 wherein the substrate material is selected from the group consisting of iridium, aluminum, carbon/carbon composite, iron, and stainless steel. 
     
     
       8. The method of claim 1 wherein the noble gas is selected from the group consisting of argon, krypton, and xenon.